﻿using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;

namespace OddNumber
{
    class Program
    {
        static void Main(string[] args)
        {
            int numberN = int.Parse(Console.ReadLine());
            Dictionary<string, int> numbers = new Dictionary<string,int>();
            for (int i = 0; i < numberN; i++)
            {
                string currentInput = Console.ReadLine().Trim();
                if (numbers.ContainsKey(currentInput))
                {
                    numbers[currentInput]++;
                }
                else
                {
                    numbers.Add(currentInput, 1);
                }
            }
            foreach (var item in numbers)
            {
                if (item.Value%2 !=0)
                {
                    Console.WriteLine(item.Key);
                    break;
                }
            }
        }
    }
}
